1. Field of the Invention
This invention pertains to hatch covers in general and in particular to hatch covers used on railway hopper cars.
2. Description of the Prior Art
Prior art hatch covers having rotatable hand wheels hve generally involved mounting pivoting threaded eye-bolts and three small hand wheels about a hatch cover and tightening each wheel after its eye-bolt is placed in a U-shaped slot of the hatch cover. Another type of hatch cover device, such as that disclosed in Carney U.S. Pat. No. 3,155,052 (1964), uses a single hand wheel in combination with both a threaded shaft and arms that permit the cover to be moved vertically and then swung aside to provide access for the hopper.
These types of hatch cover locking devices have met with limited use but there has been no widespread acceptance because the multiple hand wheel arrangement requires excessive time to open or close a hatch cover, and, the hand wheel/arm arrangement can result in inadequate sealing and is undesirable for certain applications because the locking mechanism is exposed to the material within the hopper which could result in contamination.